www.ukbutterflies.co.uk

Hi,

I suspect that most of the Chalkhills we saw were coridon but I'm not so sure about these two. They were distinctly greyer and duller that the rest and so I wonder could they be hispana?
Cheers,

Robin

I spent a long time some years ago studying all available pictures of coridon and hispana to see if there were any constant differences. At the time, I thought I found some, principally relating to the extent of blue in the apical region of the forewing, but since then I have found plenty of coridon that match hispana very closely. The following, taken this year, is definitely coridon, unless I have discovered a new species for Switzerland:



Given that yours are rather worn, I would be sceptical of attempts to confirm the identity from the ups alone - they both look quite consistent with coridon to me. I would be interested to know the date in June they were taken and how their state of wear and tear compared with that of definite coridon seen in the area.

Guy

Based on various sources, there seems to be some consistency with the following dates of emergence:

Chalkhill Blue (coridon)
Late June to Early October

Provence Chalkhill Blue (hispana)
Mid-April to late June
August to early October

Spanish Chalkhill Blue (albicans)
Mid-June to August

So anything seen in June looking absolutely worn has (I believe) to be a first-brood hispana. Since albicans has a different appearance, anything fresh in June I'd put down as coridon.

Cheers,

- Pete

The Lafranchis ID book rather suggests that you were (or might have been) out of range for albicans. You might want to check your exact location against Lafranchis’ distribution map.

Hispana in Var is almost finished by mid June. The altitude effect of where you were may well extend that flight period, but it would be guessing to ID on flight period alone unless it is very clear.

Coridon and hispana males can be differentiated quite easily when fresh as hispana has a distinct yellowish tinge and coridon is a sharp silvery blue, but this wears off quite quickly and they become almost inseparable, as Guy says, from the upperside alone. There are subtle differences in the undersides and if you have an underside shot, this could be useful evidence.

Roger

I don't want to hijack this thread but given the above comments, I thought I'd post these from Drome 10/ 6/ 2009 which I have thought were Provencal ChB....

what do you think??

Given the date, I'd say Provence CHB.

Cheers,

- Pete

I would say that these are all hispana, Paul. It is easier to extract the text from my coridon page:

"Coridon and Provence Chalk-hill Blue (L. hispana) can be difficult to tell apart, especially so from the female upperside. The male upperside of hispana is a rather duller silvery blue, often being rather yellowish at the margins. Coridon can be very variable, just to make things more difficult, but it is single-brooded and a relatively late emerger, even in the far south of France, so any specimens seen in May or early June will almost certainly be hispana, and this has been borne out by other indicators. There is a second generation of hispana later in the summer, when they do fly at the same time and locations, although hispana is on the wing into October. I have also found that the inner edge of the hispana unf lunules are often (usually/always?) larger and smudgily indistinct. Whether this holds up in all cases, I have yet to ascertain, but it has seemed consistent so far. Lafranchis says that the coridon unh is tinged brown and contrasts with the paler grey unf, while the hispana unh is also pale grey and there is minimal colour contrast; this seems to be true but there are grey (sic) areas."

Your #2 looks 100% hispana from the smudgy margin test, and #1 looks very good, and #3 also albeit rather worn. Lafranchis' colour contrast works well on #2 and #3 but not so well on #1 (hence my comments).

Roger

thanks very much Pete and Roger, I'm pleased and relieved!!

Your second picture is another Lysandra lacking a cell spot (recently, it was Adonis blue we were discussing).

In Switzerland, chalkhill blue flies from early June in hot years (7th June in 2003 - the year of la canicule ). In 2010 it remained on the wing into November and always flies in October. So it's good to have Roger's non-date-related criteria.

Guy